JP7208233B2 - Method and apparatus for detecting surface defects in glass sheets - Google Patents

Description

Cross-reference to related applications

This application claims the benefit of priority under 35 U.S.C. incorporated herein.

FIELD OF THE DISCLOSURE The present disclosure relates to optical inspection methods and apparatus, and more particularly to methods and apparatus for detecting surface defects in sheets of material, such as glass sheets.

Transparent material sheets such as glass, gems or minerals (e.g. sapphire) or polymer sheets in a variety of different devices including display panels such as LCD (liquid crystal display) panels and as protective covers for such panels It is used in the use of Such display devices and panels including them are being manufactured to be thinner and lighter, and along with this, it is desired that the material sheets be thinner and lighter.

A typical transparent sheet for a display panel or cover is made using a glass substrate. The original or starting glass substrate is thinned using mechanical treatment such as grinding and polishing, chemical treatment such as etching and polishing to the thickness desired for the final glass sheet (e.g., about 0.1 mm to about 0.7 mm) can be achieved. Surface defects can be formed during the thinning process. For example, during chemical thinning, imperfections in the form of dimples and/or bumps can be formed, also referred to as "dimples" or "pimples", respectively. Defects typically range from about 10 micrometers (μm) to several millimeters (mm) laterally, with typical vertical dimensions (i.e., depth to surface average, or height). ) can be as large as 1/4 micrometer. Since such defects in optical displays are readily visible, thinned glass substrates are inspected for surface defects and the defects removed or substrates with defects destroyed. should.

Manual methods are currently used to inspect sheets of material for defects. Unfortunately, manual inspection is labor intensive, inconsistent, and time consuming. For example, it can take many hours to inspect large production size sheets. Furthermore, it can be difficult to identify the orientation of the defect. That is, the detection device may not exhibit isotropic detection capabilities.

There is a need for a detection device that can detect defects, for example scratches, in sheets of material, such as large sheets of glass, without being affected by the orientation of the defect.

According to the present disclosure, a method for detecting defects in a glass sheet surface is disclosed, the method comprising collimating a light beam emitted from a light source and intersecting the collimated light beam with a beam splitter. . The beam splitter directs a first portion of the crossed parallel light beams onto the first surface of the glass sheet such that the directed portion of the crossed parallel light beams illuminates the first surface of the glass sheet. It is something to do. A first portion of the light that illuminates the first surface of the glass sheet is reflected by the first surface and a second portion of the light that illuminates the first surface of the glass sheet is scattered by the defect. The method also includes receiving the reflected light and the scattered light with a first lens element, the first lens element directing the reflected light and the scattered light to the reverse aperture and the reflected light to the reverse aperture. The scattered light is blocked by the aperture and the scattered light is transmitted by the reverse aperture. The method further includes directing the scattered light transmitted by the reverse aperture to an imaging device using the second lens element to detect the scattered light.

The light source can be a laser, light emitting diode, or white light source. A light source may contain or emit one or more visible light wavelengths.

The method further includes that reflected light is blocked by an opaque disc contained in the reverse aperture and scattered light is transmitted by a transparent area surrounding the opaque disc.

In some embodiments, a second portion of the collimated light that intersects the beam splitter is then incident on the beam dump.

In some embodiments, the glass sheet is moved from a first position where the directed portion of the crossed parallel light beams does not illuminate the surface of the glass sheet. The method further comprises monitoring the glass sheet as it is moved from the first position to the second position; monitoring the light emitted by the light source when in the first position and adjusting the output of the light source if the output of the light source varies from the predetermined output; and moving the glass sheet to the second position. and disabling monitoring of the light emitted by the light source when positioned.

The first and second lens elements can be included in a lens assembly, and in some embodiments the method further comprises focusing the lens assembly on a second lens element opposite the first major surface. Defocusing to the surface, or defocusing the lens assembly to a position between the first and second major surfaces.

In yet another embodiment, a method of detecting defects in a surface of a glass sheet is described, the method comprising transporting the glass sheet in a transport direction, wherein a plurality of defect detection modules are positioned across the lateral dimension of the glass sheet. arranged in an array, each defect detection module having means for collimating the light beams emitted by the light source and means for intersecting the parallel light beams with a beam splitter, comprising: The beam splitter directs a first portion of the crossed parallel light beams onto the first surface of the moving glass sheet such that the directed portion of the crossed parallel light beams strikes the first surface of the glass sheet. wherein a first portion of the light illuminating the first surface of the glass sheet is reflected by the first surface and a second portion of the light illuminating the first surface of the glass sheet comprises: and means for receiving the reflected and scattered light with a first lens element, the first lens element directing the reflected and scattered light to the reverse aperture. the reflected light is blocked by the reverse aperture and the scattered light is transmitted by the reverse aperture; and means for detecting the scattered light directed toward the.

The first array of defect detection modules can be, for example, a linear array.

In some embodiments, the transport direction is orthogonal to the direction of the linear first array of defect detection modules.

In some embodiments, the plurality of defect detection modules may include a second array of defect detection modules opposite the first array of defect detection modules.

In some embodiments, the glass sheets are crossed in the transport direction from a first position where the directed portion of the crossed parallel light beams does not illuminate the first surface of the glass sheet for each defect detection module. The parallel beams are conveyed to a second position to illuminate the first surface of the glass sheet, and the method further comprises moving the glass sheet from the first position to the second position. monitoring the sheet; and for each defect detection module, monitoring the light emitted by the light source when the glass sheet is in the first position, and if the output of the light source varies from the predetermined output, and for each defect detection module, disabling monitoring of light emitted by the light source when the glass sheet is in the second position.

For each defect detection module, the first and second lens elements can be included in the lens assembly, and the method further comprises defocusing the lens assembly, e.g., focusing within the thickness of the glass sheet. A shifting step may be included.

In yet another embodiment, an apparatus for detecting surface defects in a sheet of material is disclosed, wherein the apparatus blocks a light source and a first portion of crossed parallel light and directs it toward a first surface of a glass sheet. a beam splitter configured to direct a portion of crossed parallel light to illuminate a first surface of the glass sheet, the first portion of the light illuminating the first surface of the glass sheet being , a second portion of the light reflected by the first surface of the glass sheet and illuminating the first surface of the glass sheet is scattered by the defect; a beam splitter; a lens assembly including a lens element; a reverse aperture positioned between the first lens element and the second lens element and configured to block background light and transmit scattered light; and the transmitted scattered light. and an imaging device configured to detect the

Additional features and advantages of the embodiments disclosed herein will be set forth in the following detailed description, which will be readily apparent to those skilled in the art, in part from that description, or from the following detailed description, claims. , and by practicing the embodiments described herein, including the accompanying drawings.

It should be understood that both the foregoing general description and the detailed description of the embodiments that follow are intended to provide an overview or framework for understanding the nature and features of the embodiments disclosed herein. is. The accompanying drawings are provided to provide a further understanding, and are incorporated in and form a part of this specification. The drawings illustrate various embodiments of the disclosure and together with the description serve to explain the principles and operation of the disclosure.

1 is a perspective view of a glass sheet under inspection, showing how defect observation depends on defect orientation and illumination angle. FIG. 1 is a perspective view of a glass sheet under inspection, showing how defect observation depends on defect orientation and illumination angle. FIG. 1 is a perspective view of a glass sheet under inspection, showing how observation of orthogonally illuminated defects can be made independent of defect orientation; FIG. 1 is a perspective view of a glass sheet under inspection, showing how observation of orthogonally illuminated defects can be made independent of defect orientation; FIG. 1 is a schematic diagram of an exemplary defect detection apparatus according to embodiments of the present disclosure; FIG. FIG. 4 is a schematic diagram of another exemplary defect detection apparatus; FIG. 4 is a schematic diagram of yet another exemplary defect detection apparatus; FIG. 4 is a schematic diagram of yet another exemplary defect detection apparatus; FIG. 4 is a schematic diagram of another exemplary defect detection apparatus; 4 is a series of photographs of various defects captured using an exemplary defect detection apparatus described herein;

Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like parts. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes the range from the one particular value to the other particular value. Similarly, when a value is expressed as an approximation, eg, preceded by "about," it will be understood that the particular value forms another embodiment. Further, it will be understood that the endpoints of each range are important both relative to the other endpoint and independently of the other endpoint.

Directional terms used herein, e.g., up, down, right, left, front, back, top, bottom, etc., refer to the drawings shown and are intended to refer to absolute orientations. not intended to

Unless otherwise stated, any method presented herein should be construed to require that the steps be performed in a particular order, or that any apparatus be in a particular orientation. not intended to Thus, neither the method claims do not actually recite the order in which the steps are performed, nor the device claims either actually recite the order or orientation of the individual components, or rather the If, in a claim or written description, neither the steps are limited to a particular order nor the specific order or orientation of the components of the apparatus, then at all points the order and orientation are to be inferred. not intended at all. This applies to any interpretation based on the absence of description, and such interpretations do not include logic about the sequence of steps, operational flow, component order or component orientation, grammatical structure. or the mere meaning derived from punctuation, as well as the number or kind of embodiments described in the specification.

As used herein, the singular indefinite and definite articles in the original English include the plural unless the context clearly dictates otherwise. Thus, for example, reference to an element with an indefinite article includes aspects having two or more of such elements, unless the context clearly dictates otherwise.

As used herein, the terms "exemplary," "example," or variations thereof are used to mean as an example, instance, or illustration. Any "exemplary" or "example" aspect or design described herein is not necessarily to be construed as preferred or advantageous over other aspects or designs. Further, the examples are provided merely for clarity and understanding, and are not intended to limit or limit the disclosed subject matter or relevant portions of the present disclosure in any way. It will be appreciated that further or alternative myriad examples of different ranges could be provided, but have been omitted for the sake of brevity.

For example, current methods of detecting surface defects in a sheet of material of transparent material, such as a glass sheet, involve projecting parallel light through the glass sheet as the glass sheet is conveyed in the conveying direction, and , illuminated by parallel light) on the sensor. Embodiments of the present disclosure may be suitable for use with either opaque or translucent materials, although such embodiments may be used for transparent materials with separate electrodes located adjacent opposing major surfaces. It has been shown to be particularly effective, as surface defects can be imaged from both sides of the glass sheet without the need for any equipment. However, the orientation of a defect relative to the direction and angle of light used to illuminate a defect, such as a scratch, can affect the ability to detect the defect. For example, scratches are typically elongated defects and thus may exhibit identifiable directions. Such elongated defects may be aligned with the direction of illumination, perpendicular to the direction of illumination, or at an angle therebetween (it should also be noted that certain defects may not be perfectly linear). . Imaging of such defects can be hindered if illuminated at a low (grazing) angle to the plane of incidence and the direction of the defect is aligned with the illumination direction.

FIG. 1 shows an exemplary glass sheet 10 including a first major surface 12 and a second major surface 14 opposite the first surface 12, the first and second major surfaces 12, 14 define a thickness T between them. Glass sheet 10, in some embodiments, can be a transparent glass sheet, eg, transparent to irradiating light. As used herein, the term transparent shall be interpreted to mean that the transparency of the material is greater than or equal to 90% at the wavelength of the illuminating light (eg, center wavelength). The first surface 12 is parallel or substantially parallel to the second surface 14 and has a thickness T of, for example, about 2 mm or less, such as about 1.5 mm or less, about 1 mm or less, about 0.7 mm or less. , about 0.5 mm or less, about 0.3 mm or less, or about 0.1 mm or less. However, since surface imperfections, in particular those facing the detection device, are generally insensitive to the thickness of the material sheet, in a further embodiment the thickness T may be greater than 2 mm. According to this embodiment, the first surface 12 is assumed to include a scratch 16 that begins on the side of the glass sheet and extends perpendicular to the incident light 18 at low angles of incidence with respect to the first surface 12 . showing. The glass sheet 10 is transported in a transport direction 20 which is also perpendicular to the scratches 16 . Incident light 18 is then scattered by the scratch 16 in a direction substantially perpendicular to the direction of the scratch. That is, if we consider the incident light to lie in a plane orthogonal to the surface of the glass sheet and also orthogonal to the scratch, then the scattered light 22 from the scratch is generally located in that same plane and scattered Light 22 may be collected by detector 24 . Since this scattered light is not usually or necessarily planar, it is only a simplification but sufficient for illustrative purposes.

FIG. 2 shows an exemplary glass sheet 10 arranged such that the scratches 16 are aligned parallel to the incident light 18 and also parallel to the transport direction 20 . Incident light 18, which illuminates the scratch, again at a low angle to the first surface 12, is then scattered by the scratch in directions along the direction of the scratch. In this case, whether the scattered light 22 can be detected depends on the direction of the scratch and the angle of incidence. If the angle of incidence with respect to the surface of the glass sheet 10 is small, eg, within 20 degrees, then the angle of scattering will also generally be small. The scattered light in this case may not be received by the detector 24 or may be sufficiently weak to not be easily detected. Thus, FIGS. 1 and 2 show that the combination of low angle illumination and the directional nature of defects creates problems in defect detection.

3 and 4, on the other hand, show the case where the incident light 18 is directed orthogonally or substantially orthogonally to the first surface 12 of the glass sheet 10 (in the drawings, the incident light 18 is detected 3 and 4), the ability to detect a scratch is independent of the orientation of the scratch (for simplicity, in FIGS. 16 are shown in a single orthogonal plane). Accordingly, FIG. 3 shows the glass sheet 10 moving in a transport direction 20 perpendicular to the scratch 16 and the scattered light 22 extends in a plane perpendicular to the scratch 16 . FIG. 4 shows the glass sheet 10 moving in a transport direction 20 parallel to the scratch 16 and scattered light 22 extends in a plane parallel to the scratch 16 . In both cases, the scattered light 22 can be received by a detector 24 that includes a detection axis orthogonal to the principal plane of the glass sheet.

Based on the above description, FIG. 5 illustrates an exemplary detection apparatus 100 configured for isotropic defect detection of surface defects in a sheet of material using the principals of FIGS. For purposes of illustration and not limitation, the sheet of material for which defects are to be detected is described as a transparent glass sheet, such as a visually transparent glass sheet suitable for manufacturing display devices. Defects therefore include, but are not limited to, bumps, dents (such as pits caused by molding operations), surface residues, scratches, stones (e.g., unmelted material used to make glass sheets). materials), attached glass chips, fibers or other particles attached to the surface of the sheet, surface inclusions, stains, and the like. As used herein, isotropic defect detection refers to detecting surface defects independent of the orientation of the defect, particularly within the plane of the glass sheet surface. The apparatus 100 includes a light source 102, a collimator 104 arranged to collimate the light 106 emitted from the light source 102, a beam splitter 108 positioned to block the collimated light 106, a first front lens element 112 and a second lens element 112. It includes a lens assembly 110 including two rear lens elements 114 and a detection module 101 including a reverse aperture 116 located between a first lens element 112 and a second lens element 114 . Lens assembly 110 may include, for example, a telecentric lens.

Detection module 101 may further include imaging device 118 , which includes imaging sensor 120 . In some embodiments, the imaging sensor 120 controls the control unit depending on how the images acquired by the imaging sensor 120 are viewed and/or stored for later viewing and/or analysis. , optionally to a computing system, optionally to a monitor (display device), and optionally to a recording device.

The detection device 100 may further include a transport device 122 configured to transport the glass sheet in the transport direction 20 past the detection module 101 . Transport device 122 may include, for example, one or more endless belts 124 arranged to move glass sheet 10 in transport direction 20 . Transport device 122 is positioned such that first surface 12 upon which light from light source 102 (eg, light reflected by beam splitter 108) is incident is unobstructed (eg, matches the field of view of lens 110, gaps 126 of unobstructed size and location). For example, the transport device 122 may include at least two endless belts arranged in loops with a gap between the ends of the loops. In other embodiments, the transport apparatus 122 may include air bearings, such as multiple air bearings, arranged side by side with a gap between the ends of the air bearings, the glass sheets 10 from the first air bearing over the gap to the next air bearing. Although the glass sheet 10 is shown to be conveyed in a horizontal orientation, the apparatus and methods disclosed herein may be configured in other orientations. For example, the glass sheet 10 can be positioned in a vertical orientation or in an off-vertical orientation (eg, at an angle of 5 to 20 degrees and supported by air bearings). Other glass sheet orientations and transport methods can be readily envisioned by those skilled in the art, and the embodiments described herein are specifically limited to the configurations shown in the accompanying drawings. is not.

Still referring to FIG. 5, light 106 emitted by light source 102 is collimated by collimator 104 and collimated light 128 is incident on beam splitter 108 . Beam splitter 108 splits incident parallel light 128 into two beams, one of which (represented by rays 130) is transmitted through beam splitter 108 (represented by rays 132). ) the second beam is reflected orthogonally or nearly orthogonally downward toward the first surface 12 of the glass sheet 10 . As used herein, the term substantially orthogonal means, e.g., within 20 degrees, such as within 10 degrees, within 5 degrees, or within 1 degree, from normal to a reference surface or direction, such as the first surface. intended to mean that Light 130 transmitted through beam splitter 108 may be captured (eg, absorbed) by first beam dump 134 . For example, first beam dump 134 may include a component having a surface composed of a dark (eg, black) material to absorb light incident on the beam dump. The surface of the component may be painted or otherwise coated with a light absorbing material to cause the component to absorb, examples of light absorbing material are matte black paint, carbon layer , an anodized layer, or any other suitable absorbent layer or material. In embodiments, the absorbing component of the first beam dump 134 is at an angle to the beam direction of the transmitted light 130 such that light reflected from the beam dump 134 is directed toward the light source 102 also It may also be prevented from being reflected by the beam splitter 108 in a direction towards the detector 118 . In embodiments, the absorbent component can be a coating plate, but in further embodiments, the absorbent component can include multiple coating plates arranged at an angle to each other.

A first portion of the second beam 132 incident on the first surface 12 of the glass sheet 10 is reflected from the first surface 12 , transmitted through the beam splitter 108 , and illuminated by the lens assembly 110 as background light 138 . A second portion of the second beam 132 that is focused as and incident on the defect (e.g., scratch 16) is scattered by the defect in a direction generally toward the lens assembly 110 and is thus captured as scattered light 140. . Additionally, another (third) portion 142 of light 132 reflected by beam splitter 108 may be transmitted through glass sheet 10 and absorbed by a second beam dump 144 . For example, like first beam dump 134, second beam dump 144 may include a component having a surface that includes a dark (eg, black) material to absorb light incident on the material. The surface of the component may be painted or otherwise coated with a light absorbing material to cause the component to absorb, examples of light absorbing material are matte black paint, carbon layer , an anodized layer, or any other suitable absorbent layer or material. In an embodiment, the absorbing component is at an angle to the beam direction 146 (perpendicular to the major surfaces 12, 14) of the portion of the collimated light transmitted through the glass sheet 10, and the second beam Light reflected by dump 144 may be prevented from being directed toward imaging device 118 or light source 102 . In embodiments, the absorbent component can be a single coating plate, but in further embodiments, the absorbent component can include multiple coating plates arranged at an angle to each other.

Still referring to FIG. 5, the background light 138 is focused by the front lens element 112 to an opaque central disk 148 of the reverse aperture 116 located at the rear focal plane 150 of the first lens element 112, There, the background light 138 is absorbed. Light 140 scattered by defect 16 is transmitted through a transparent region 152 surrounding an opaque central disk 148 of reverse aperture 116 and is further coupled by second lens element 114 to imaging sensor 120 of imager 118 . be burned.

Light source 102 may include a laser, or in other embodiments, light source 102 may include light emitting diodes (LEDs). A laser or LED may emit light at any suitable wavelength or group of wavelengths that imager 118 can detect. For example, in embodiments, lasers or LEDs can emit light in visible wavelengths (eg, in the range of about 400 nanometers (nm) to about 700 nm). In some embodiments, light source 102 may include a white light source, such as a white light source, eg, an incandescent light bulb.

Beam splitter 108 may be any suitable beam splitter. For example, in some embodiments beamsplitter 108 can be a half-plated silver mirror, such as a pellicle mirror. Other beamsplitter designs may be used, depending on the wavelength of the incident light, the type of defects intended to be detected, etc., and such designs are well known to those skilled in the art.

Imaging device 118 may be a camera or other suitable imaging device, such as a line scan camera, and imaging sensor 120 is a line sensor aligned orthogonally or substantially orthogonally to transport direction 20. sell.

In some embodiments, reverse aperture 116 includes an opaque central disk 148 supported by a wire or other thin material extending from outer material 154 , the outer material in combination with opaque central disk 148 . , defines an annular transparent region 152 surrounding the opaque central disk 148 . However, such support members can interfere with isotropic detection. Thus, in a preferred embodiment, the reverse aperture 116 comprises a transparent plate, such as a glass plate, having a masking material deposited thereon, the masking material being the inner mask (i.e., the opaque central disk 148); and an outer mask 154 defining the perimeter of the transparent region 152 (which is an annular transparent region 152 and is thus defined between the outer mask 154 and the opaque central disc 148), wherein the opaque support or connecting elements are It does not stretch between the outer mask material and the inner mask material. The reverse aperture 116 is then permanently seated within the lens 110 or the lens 110 is configured with a port or other opening to facilitate insertion of the reverse aperture 116 and/or Removal (or insertion and/or removal of any other desired opening or filter) may be allowed.

A photodiode (not shown) may be positioned to monitor the laser light from the light source, eg, a laser photodiode, to stabilize the output from the light source. The output from the light source may be detected and an appropriate signal sent over data line 161 to controller 160, thereby establishing a control loop to monitor and adjust the light source output. For example, if the power of the laser source deviates from the predetermined power set point, the controller 160 adjusts the laser (e.g., photodiode) power regulation through the data line 162 so that the laser power is at the predetermined power set point. output set point.

According to embodiments described herein, if no glass sheet is being inspected (e.g., there is no glass sheet 10 in or adjacent to gap 126), controller 160 causes laser can be programmed to control However, when inspecting a glass sheet, reflected light, eg, light reflected from beam splitter 108 in a direction toward light source 102, may enter the laser and be scattered. This can make the output of the photodiode appear larger than it actually is. As a result, the controller 160 tries to lower the laser power. Therefore, the actual laser power may be too low for inspection.

To solve these problems, a glass sheet proximity sensor 163 can be deployed to detect the glass sheet. Knowing the glass sheet transport speed, using a timing circuit in controller 160, controller 160 disables feedback control whenever a glass sheet is in front of the detector. Thus, feedback control of the laser is enabled when there is no glass sheet under inspection (eg, the glass sheet is not over (eg, obstructs) the gap 126). Alternatively, the presence or absence of a glass sheet in the gap may be detected directly, in which case velocity and position calculations are not required. The light source output may also be used with other light sources, such as LED light sources.

Based on the above description, it will be clear that the arrangement of the components of the detection device may be varied to achieve, for example, a more compact device. FIG. 6 shows another exemplary detection apparatus 200 configured for isotropic defect detection. The detection apparatus 200 includes a detection module 202 including a light source 204, a collimator 206 arranged to collimate light 208 emitted from the light source 204, a beam splitter 210, a first front lens element 214 and a second rear lens element 214. It includes a lens assembly 212 including a lens element 216 and a reverse aperture 218 positioned between a first lens element 214 and a second lens element 216 . Lens assembly 212 may include, for example, a telecentric lens. Detection module 202 may further include imaging device 220 including imaging sensor 222 . Any one or more of the above components may rest on frame 224 to establish and/or maintain spatial relationships between selected components.

Detecting device 200 may optionally include a field stop 226 arranged to block an outer region of light emitted by light source 204 . The detector 200 also includes a focusing device 228 configured to move the lens 212 relative to the beam splitter 210 (and glass sheet 10), thereby focusing the lens assembly to the first principal plane. 12 and the second surface 14. Therefore, the focus of the lens 212 can be moved from the first major surface 12 to the second major surface 14 or to any point across the thickness T between the first and second major surfaces of the glass sheet. sell. Focusing device 228 may be, for example, a linear rail or stage assembly that allows lens 212 to move relative to beam splitter 210 and glass sheet 10 . That is, moving lens 212 changes the optical path length between the lens assembly and the glass sheet. Accordingly, in some embodiments, lens assembly 212 is mounted to frame 224 via focusing device 228 and the position of lens assembly 212 is adjusted by adjusting the position of focusing device 228. sell. In some embodiments, the focus device 228 may be manually adjusted by a screw assembly, but in further embodiments the focus device is a motor, e.g., a servomotor, engaged with the focus device 228. can include regulation via In some embodiments, focusing may be accomplished via remote control or even automatically. A person skilled in the art can easily arrange the appropriate components to achieve remote or automatic focus control. It will also be readily appreciated that the focusing device 228 may be used with other embodiments described herein.

The operation of this embodiment is the same as the operation of the above embodiment. Light sources 204 are arranged such that emitted light 208 is directed orthogonally or substantially orthogonally to first major surface 12 of glass sheet 10 . That is, light 208 is emitted in a direction orthogonal to first major surface 12 along first optical axis 224 , and second optical axis 226 of lens 212 is parallel to first major surface 12 . (and orthogonal to the first optical axis 224). Emitted light 208 is collimated by collimator 206 and collimated light 228 enters beam splitter 210 . Beam splitter 210 splits incident collimated light 228 into two beams, one beam (represented by rays 232) being transmitted through beam splitter 210 toward first surface 12 of the glass sheet, A second beam (represented by ray 234 ) is reflected from beam splitter 210 in a direction orthogonal to transmitted beam 230 toward first beam dump 236 . Light 234 reflected by beam splitter 210 may be captured (eg, absorbed) by first beam dump 236 . For example, first beam dump 236 may include an absorbing component configured to absorb light incident on the absorbing component. The absorbing component can be made absorbing, for example, by painting or otherwise coating the surface of the absorbing component with a light absorbing material, an example of a light absorbing material being matte black paint. , a carbon layer, or any other suitable absorbent material. In embodiments, the absorbing component may be at an angle to the direction of propagation of the reflected beam 234 to prevent light that may be reflected from the beam dump from being directed back towards the light source 204 . .

A portion of the first beam 232 incident on the first surface 12 of the glass sheet 10 is reflected from the first surface 12 of the glass sheet 10 back toward the beam splitter 210 and then reflected by the beam splitter. 210 reflected in a direction toward lens assembly 212 and collected as background light by lens assembly 212 while incident on defects in first major surface 12 (and/or second major surface 14). A second portion of beam 232 of 1 is scattered by the defect in a direction generally toward lens assembly 212 (after reflection from beamsplitter 210) and captured by lens assembly 212 as scattered light (for simplicity , both the reflected light from the first surface 12 and the scattered light are shown as a single ray 238). Nonetheless, the behavior of the reflected light from the first surface 12 of the glass sheet 10, the behavior of the scattered light, and the interaction of the reflected and scattered light with the reverse aperture 218 are different for the detection module 101 and the reverse aperture 116. is the same as described in

In addition, another (third) portion 240 of the light 232 transmitted through the beam splitter 210 and incident on the first surface 12 is transmitted through the glass sheet 10 and by a second beam dump 242 It can be captured (eg, absorbed). For example, similar to first beam dump 236, second beam dump 242 can include an absorbing component configured to absorb light incident on the absorbing component. The sheet of material can be made absorbent, for example, by painting or otherwise coating the absorbent component with an absorbent material, examples of which are matte black paint, a carbon layer, or , may include any other suitable absorbent material. In an embodiment, the absorbing component is at an angle to the incident beam 240 transmitted through the glass sheet 10 such that light reflected from the second beam dump 242 is directed toward the imager 220 or light source 204. It can prevent it from being reflected back in direction. In embodiments, the absorbing component can be a plate coated with light absorbing material, but in a further embodiment, the absorbing component can include multiple coated plates arranged at angles to each other.

Still referring to FIG. 6, background light is focused by the front lens element 214 onto an opaque central disc 244 of the reverse aperture 218 located at the rear focal plane of the first lens element 214, where Background light is absorbed. Light scattered by defects (e.g., scratches) 16 is transmitted through a transparent region 246 surrounding an opaque central disk 244 of reverse aperture 218 and is further directed by second lens element 216 to imager 220 . The imaging sensor 222 is focused.

Based on the above description, it will be apparent that in some instances the arrangement of components will image a small portion of the target glass sheet, particularly when the glass sheet is conveyed along conveying direction 20. . Thus, in embodiments, the detection apparatus 200 (or 100) may include a plurality of detection modules 202 (or 101) arranged in an array facing and adjacent to the glass sheet 10. FIG. In some embodiments, multiple detection modules may be arranged in a facing relationship, as shown in FIG. Further, in embodiments, multiple rows of detection modules may be used, and in some embodiments, opposing rows of detection modules may be used, as shown in FIG. In some embodiments, opposing rows of detection modules 202 (or 101) are offset such that the optical axis of a lens assembly in one row extends between the opposing lens assemblies in an opposing row. (see Figure 9). That is, the lens assemblies are positioned opposite the gap between the two lens assemblies of opposing rows of detection modules. In other embodiments, the optical axes of opposing lens assemblies may coincide.

FIG. 10 contains a series of images of different defects observed using the detection apparatus of the present disclosure. The images demonstrate that a wide variety of surface defects can be detected using embodiments of the present disclosure.

It will be apparent to those skilled in the art that various modifications and alterations can be made to the embodiments of the disclosure without departing from the spirit and scope of the disclosure. Accordingly, the present disclosure is intended to cover such modifications and variations insofar as they come within the scope of the appended claims and their equivalents.

Hereinafter, preferred embodiments of the present invention will be described item by item.

Embodiment 1
In the method for detecting defects on the surface of a glass sheet,
collimating a beam of light emitted from a light source;
intersecting the parallel light beam with a beam splitter, the beam splitter directing a first portion of the crossed parallel light beam to a first surface of a glass sheet to direct the crossed parallel light beam to a first surface of a glass sheet; said directed portion of a beam of light illuminating said first surface of said glass sheet, said first portion of said light illuminating said first surface of said glass sheet illuminating said first surface of said glass sheet; a second portion of the light reflected by one surface and illuminating the first surface of the glass sheet is scattered by a defect;
a step of receiving the reflected light and the scattered light using a first lens element, the first lens element directing the reflected light and the scattered light to a reverse aperture, and the reflected light is intercepted by the reverse aperture, the scattered light being transmitted by the reverse aperture;
and directing the scattered light transmitted by the reverse aperture to an imaging device using a second lens element to detect the scattered light.

Embodiment 2
3. The method of embodiment 1, wherein the light source is a laser.

Embodiment 3
3. The method of embodiment 1, wherein the light source comprises one or more visible light wavelengths.

Embodiment 4
3. The method of embodiment 1, wherein a second portion of the collimated light that intersects the beam splitter is then incident on a beam dump.

Embodiment 5
The glass sheet is moved from a first position where the directed portion of the crossed parallel light beam does not illuminate the surface of the glass sheet so that the directed portion of the crossed parallel light beam is moved to a second position to illuminate said surface of the sheet;
The method further includes:
monitoring the glass sheet as it is moved from the first position to the second position;
monitoring the light emitted by the light source when the glass sheet is in the first position and adjusting the output of the light source if the output of the light source varies from a predetermined output; When,
and disabling monitoring of the light emitted by the light source when the glass sheet is in the second position.

Embodiment 6
wherein the first and second lens elements are included in a lens assembly;
The method further includes:
defocusing the lens assembly to a second surface of the glass sheet opposite the first surface;
2. The method of embodiment 1, comprising:

Embodiment 7
wherein the first and second lens elements are included in a lens assembly;
The method further includes:
shifting the focus of the lens assembly to a position between the first surface and a second surface opposite the first surface;
2. The method of embodiment 1, comprising:

Embodiment 8
In the method for detecting defects on the surface of a glass sheet,
transporting the glass sheet in a transport direction adjacent to a plurality of defect detection modules arranged in a first array across the lateral dimension of the glass sheet;
including
Each said defect detection module includes:
means for collimating a beam of light emitted from a light source;
means for intersecting the parallel light beam with a beam splitter, the beam splitter directing a first portion of the intersected parallel light beam toward a first surface of the moving glass sheet; causing said directed portion of said crossed parallel light beam to illuminate said first surface of said glass sheet, said first portion of said light illuminating said first surface of said glass sheet wherein a second portion of the light reflected by the first surface and illuminating the first surface of the glass sheet is scattered by a defect;
means for receiving the reflected light and the scattered light using a first lens element, the first lens element directing the reflected light and the scattered light to a reverse aperture, and the reflected light is means intercepted by said reverse aperture, said scattered light being transmitted by said reverse aperture;
and means for directing the scattered light transmitted by the reverse aperture to an imaging device using a second lens element to detect the scattered light.

Embodiment 9
9. The method of embodiment 8, wherein the first array of defect detection modules is a linear array.

Embodiment 10
10. The method of embodiment 9, wherein the transport direction is orthogonal to the linear first array direction of the defect detection modules.

Embodiment 11
9. The method of embodiment 8, wherein the plurality of defect detection modules includes a second array of defect detection modules opposite the first array of defect detection modules.

Embodiment 12
The glass sheet is moved in the transport direction, for each defect detection module, from a first position where the directed portions of the crossed parallel light beams do not illuminate the first surface of the glass sheet. conveyed to a second position where crossed parallel beams illuminate the first surface of the glass sheet;
The method further includes:
monitoring the glass sheet as it is moved from the first position to the second position;
for each said defect detection module, monitoring said light emitted by said light source when said glass sheet is in said first position; adjusting the output of
and for each said defect detection module, disabling monitoring of said light emitted by said light source when said glass sheet is in said second position.

Embodiment 13
for each said defect detection module, said first and second lens elements are included in a lens assembly;
The method further includes:
defocusing the lens assembly,
9. The method of embodiment 8, comprising:

Embodiment 14
14. The method of embodiment 13, wherein defocusing the at least one lens assembly comprises defocusing the focus within the thickness of the glass sheet.

Embodiment 15
In the surface defect detection device for material sheets,
a light source;
a collimator arranged to collimate the light from the light source;
Directing a first portion of the collimated light orthogonally toward a first surface of the glass sheet such that the directed portion of the collimated light is directed toward the first surface of the glass sheet. wherein a first portion of the light illuminating the first surface of the glass sheet is reflected by the first surface of the glass sheet and a beam splitter, wherein a second portion of the light illuminating the first surface is scattered by a defect;
a first lens element and a second lens element, the directed portion of the collimated light, the light reflected from the first surface of the glass sheet and the first lens element of the glass sheet; a lens assembly arranged to receive light scattered from surface imperfections;
a reverse aperture located between the first lens element and the second lens element;
an imaging device positioned to receive light scattered by the defect and transmitted by the reverse aperture.

Embodiment 16
16. The apparatus of embodiment 15, wherein the reverse aperture is configured to block light reflected from the first surface.

10 glass sheet 24 detector 100, 200 detector 101, 202 detector module 102, 204 light source 104, 206 collimator 108, 210 beam splitter 110, 212 lens assembly 112, 214 front lens element 114, 216 rear lens element 116, 218 reverse aperture 118, 122 imaging device 120, 222 imaging sensor 134, 144 beam bump

Claims (8)

In the method for detecting defects on the surface of a glass sheet,
collimating a beam of light emitted from a light source;
intersecting the parallel light beam with a beam splitter, the beam splitter directing a first portion of the crossed parallel light beam to a first surface of a glass sheet to direct the crossed parallel light beam to a first surface of a glass sheet; said directed portion of a beam of light illuminating said first surface of said glass sheet, said first portion of said light illuminating said first surface of said glass sheet illuminating said first surface of said glass sheet; a second portion of the light reflected by one surface and illuminating the first surface of the glass sheet is scattered by a defect;
a step of receiving the reflected light and the scattered light using a first lens element, the first lens element directing the reflected light and the scattered light to a reverse aperture, and the reflected light is intercepted by the reverse aperture, the scattered light being transmitted by the reverse aperture;
directing the scattered light transmitted by the reverse aperture to an imaging device using a second lens element to detect the scattered light ;
The glass sheet is moved from a first position where the directed portion of the crossed parallel light beam does not illuminate the surface of the glass sheet so that the directed portion of the crossed parallel light beam is moved to a second position to illuminate said surface of the sheet;
The method further includes:
monitoring the glass sheet as it is moved from the first position to the second position;
monitoring the light emitted by the light source when the glass sheet is in the first position and adjusting the output of the light source if the output of the light source varies from a predetermined output; When,
disabling monitoring of the light emitted by the light source when the glass sheet is in the second position;
method including. 2. The method of claim 1, wherein the light source is a laser. 3. A method according to claim 1 or 2, wherein the second portion of the collimated light that intersects the beam splitter is then incident on a beam dump. wherein the first and second lens elements are included in a lens assembly;
The method further includes:
defocusing the lens assembly to a second surface of the glass sheet opposite the first surface;
4. A method according to any one of claims 1 to 3 , comprising wherein the first and second lens elements are included in a lens assembly;
The method further includes:
shifting the focus of the lens assembly to a position between the first surface and a second surface opposite the first surface;
4. A method according to any one of claims 1 to 3 , comprising In the method for detecting defects on the surface of a glass sheet,
transporting the glass sheet in a transport direction adjacent to a plurality of defect detection modules arranged in a first array across the lateral dimension of the glass sheet;
including
Each said defect detection module includes:
means for collimating a beam of light emitted from a light source;
means for intersecting the parallel light beam with a beam splitter, the beam splitter directing a first portion of the intersected parallel light beam toward a first surface of the moving glass sheet; causing said directed portion of said crossed parallel light beam to illuminate said first surface of said glass sheet, said first portion of said light illuminating said first surface of said glass sheet wherein a second portion of the light reflected by the first surface and illuminating the first surface of the glass sheet is scattered by a defect;
means for receiving the reflected light and the scattered light using a first lens element, the first lens element directing the reflected light and the scattered light to a reverse aperture, and the reflected light is means intercepted by said reverse aperture, said scattered light being transmitted by said reverse aperture;
means for directing the scattered light transmitted by the reverse aperture to an imaging device using a second lens element to detect the scattered light ;
The glass sheet is moved in the transport direction, for each defect detection module, from a first position where the directed portions of the crossed parallel light beams do not illuminate the first surface of the glass sheet. conveyed to a second position where crossed parallel beams illuminate the first surface of the glass sheet;
The method further includes:
monitoring the glass sheet as it is moved from the first position to the second position;
for each said defect detection module, monitoring said light emitted by said light source when said glass sheet is in said first position; adjusting the output of
for each said defect detection module, disabling monitoring of said light emitted by said light source when said glass sheet is in said second position;
The method that is the one that contains . In the glass sheet surface defect detection device,
a light source;
a collimator arranged to collimate the light from the light source;
Directing a first portion of the collimated light orthogonally toward a first surface of the glass sheet such that the directed portion of the collimated light is directed toward the first surface of the glass sheet. wherein a first portion of the light illuminating the first surface of the glass sheet is reflected by the first surface of the glass sheet and a beam splitter, wherein a second portion of the light illuminating the first surface is scattered by a defect;
a first lens element and a second lens element, the directed portion of the collimated light, the light reflected from the first surface of the glass sheet and the first lens element of the glass sheet; a lens assembly arranged to receive light scattered from surface imperfections;
a reverse aperture located between the first lens element and the second lens element;
an imaging device positioned to receive light scattered by the defect and transmitted by the reverse aperture ;
a conveying device configured to convey the glass sheet in a conveying direction;
a controller for monitoring the glass sheet as it is moved from the first position to the second position;
including
The conveying device moves the glass sheet from a first position where the directed portion of the crossed parallel light beam does not illuminate the first surface of the glass sheet. conveying to a second position that illuminates the first surface of the glass sheet;
The controller monitors the light emitted by the light source when the glass sheet is in the first position, and detects if the output of the light source changes from a predetermined output. A device for adjusting said power and controlling to disable monitoring of said light emitted by said light source when said glass sheet is in said second position . 8. The device of Claim 7 , wherein the reverse aperture is configured to block light reflected from the first surface.

Images